Weather Patterns
Lab 6-5
Pages 241 - 252
Weather Patterns
• AIM
• OBJECTIVE
• Understand how the • Construct field
variables we have
maps and learn to
learned about so far
identify patterns
work together to
than can be used to
create weather
predict weather.
systems.
Vocab
• Synoptic Weather Map: A map that represents
all the atmospheric variables in an area.
• Isotherm: Lines on a map connecting points
of equal temperature; generally run parallel
with the equator as temperatures decrease
with increasing distance from the equator.
• Barometric Pressure: The weight of the air
in the atmosphere
– High Pressure; nice weather
– Low Pressure; bad/rainy weather
• Isobar: Lines on a map connecting points of
equal barometric pressure.
• Convergence: Wind blowing toward the
center (cyclone)
• Divergence: Wind blowing away from the
center (anticyclone)
• Cyclone: Low
pressure system
with air moving
inward toward the
center.
• Anticyclone: High
pressure system
with air moving
away and outward
from the center.
• Air Mass: A
large body of air
with similar
pressure,
temperature and
moisture.
Acquired from a
source region.
• Source Region: An area of Earth’s
surface over which an air mass forms
and acquires its characteristics.
• Front: The
boundary between
two air masses of
different
characteristics.
Calculating Gradient
• Gradient is the rate of
change between two points
and is calculated by
dividing the difference
between two points by the
distance.
• For example: If Galveston,
TX and Kansas City, KS
are 700 miles apart and the
temperature in Galveston is
60º and the temperature in
Kansas City is 50º then . . .
• 60º - 50º = 10º (That’s
your difference)
• Distance = 700 miles
• 10º/700 = .014º/Mile
• Gradient = .014º/Mile
• Are you ready to draw your Synoptic
Weather Map? 
Map A: Isotherms
• Connect points of equal value
• Use an interval of 10°F
• Stop your lines when they go off the coast.
If more dots are
needed, add some…
Map B: Isobars
• Write the following in an empty space on the map:
Millibars
Station Model Code
1024.0
1020.0
1016.0
1012.0
1008.0
1004.0
1000.0
240
200
160
120
080
040
000
Map B: Isobars- Continued
• Draw isobars
• Use an interval of 4mb.
• Label the highest pressure with an
• Label the lowest pressure with an
Drawing isobars . . .
Map C: Wind Patterns
Draw arrows…
Map C: Wind Patterns
Now Draw Large Arrows…
Map D:
Precipitation Patterns
• Draw a line encompassing the entire area
where rain is falling.
• Lightly shade it in with pencil.
• Label the Air Masses.
Handy Dandy Earth Science
Reference Tables, pg 13
• An Air Mass is a large region of air that has
the same temperature and humidity.
• It gets its properties from hanging out in the
same region for a while.
For example:
• If the source region is the gulf of Mexico
and the air comes to Long Island…
• It will feel warm and moist to us: maritime
tropical (mT).
• If it comes from central Canada…
• It will feel cold and dry to us: continental
polar (cP)
What type of air mass?
mP
Cool & moist:
mP
Cool & Dry:
mP
cP
cT
Warm & Moist:
mT
mT
mT
Make the Synoptic Map
• Use Instruction #1 as a check list of things to put
on the map.
• Add the fronts.